Mich. Admin. Code R. 299.4904 - Contents of a hydrogeological report
Rule 904.
(1) The
purpose of a hydrogeological report for a landfill is to do all of the
following:
(a) To determine existing
groundwater quality, including the areal and vertical extent of any groundwater
contamination.
(b) To determine
background groundwater quality in the uppermost aquifer.
(c) To determine the groundwater level and to
determine compliance with the groundwater isolation requirements of these rules
and, if necessary, to define engineering modifications to reduce the
groundwater level.
(d) To define a
proposed groundwater monitoring program.
(e) To define all of the following aquifers:
(i) The uppermost aquifer and aquifers that
are hydraulically interconnected to the uppermost aquifer beneath the facility
property.
(ii) Any aquifer that is
utilized by type I and type IIa public water supplies, as defined in R
325.10502, within 1/2 mile of the proposed active work area.
(iii) Any aquifer that is utilized by type
IIb and type III public water supplies, as defined in R 325.10502, within 1,000
feet of the proposed active work area.
(f) To define the areal and vertical extent
of the site earth materials under the proposed facility.
(2) Hydrogeological studies shall be prepared
by, or under the direction of, a qualified groundwater scientist or
geologist.
(3) A determination of
hydrogeological conditions shall cover sufficient area to allow for a
definition of the potential impact of the landfill on groundwater.
(4) A hydrogeological report for a landfill
or other disposal area shall include all of the following:
(a) A determination of the background
groundwater quality.
(b) A map of
the site and surrounding area which is drawn to scale and which shows all of
the following:
(i) The distance to existing
wells and the properties in the surrounding area that have potential for
groundwater supplies. The map shall identify all soil borings and wells at the
facility and within 1/2 mile of the site, including all domestic, municipal,
industrial, oil, and gas wells for which copies of logs are available in the
public record.
(ii) Existing lakes
or ponds.
(iii) Streams, springs,
or wetlands.
(iv) The direction of
surface drainage and the direction of groundwater movement in the site
area.
(v) The locations of borings,
observation wells, and other well data used in the report.
(vi) The topography, including predominant
topographic features.
(vii) The
location of any existing open dump, underground storage tank, or other known or
potential source of groundwater contamination.
(c) Observation well records or soil borings
to locate and identify aquifers beneath the facility property. All of the
following shall be identified:
(i) Depth to
the groundwater.
(ii) Aquifer
thickness.
(iii) Vertical and
horizontal groundwater flow directions.
(iv) Vertical and horizontal flow
rates.
(d) A groundwater
elevation map which is based on stabilized water level readings, which uses
values contoured on an interval of not more than 1 foot, and which is
referenced to United States geological survey datum. Data shall be included to
determine both of the following:
(i)
Groundwater flow direction and possible variations in groundwater flow
direction.
(ii) Depth to the
groundwater.
(e)
Evaluation of site earth materials. The evaluation shall be based on soil
boring logs and the results of soil sampling from the borings to define soil
and groundwater conditions at the site, including bedrock characteristics, if
bedrock exists, within 50 feet of the proposed base of the fill. All of the
following procedures shall be utilized in collecting this data:
(i) Soil samples shall be collected by
standard soil sampling techniques.Representative uncomposited soil samples
shall be tested for by all of the following methods, unless other methods are
approved by the director:
(A) The particle
size distribution, by both sieve and hydrometer.
(B) For cohesive soils, the Atterberg limits
under ASTM D4318-94, which is adopted by reference in R 299.4135.
(C) The classification under the unified soil
classification system, under ASTM D2487-93, which is adopted by reference in R
299.4135.
(D) Undisturbed hydraulic
conductivity under the methods approved in R 299.4920.
(ii) Boring logs shall include all of the
following information:
(A) Soil and rock
descriptions.
(B) Methods of
sampling.
(C) Sample
depth.
(D) Date of
boring.
(E) Water level
measurements at the time of the boring.
(F) Soil test data.
(G) Boring locations.
(iii) All soil borings that are not converted
to observation wells shall be carefully backfilled with bentonite or cement
grout, plugged, and recorded under part 625 of the act.
(iv) All elevations shall be referenced to
United States geological survey datum.
(f) A series of geologic cross-sections or
fence diagrams that pass through representative borings and illustrate all of
the following:
(i) Existing
topography.
(ii) Soil
borings.
(iii) Soil
classification.
(iv)
Stratigraphy.
(v)
Bedrock.
(vi) Wells.
(vii) Stabilized water level
readings.
(viii) Proposed site
grades.
All of the data specified in this subdivision shall be referenced to a site map that shows the locations of all wells and borings.
(g) The
nature, extent, and consequence of any mounding that results from the diversion
of infiltration and surface water runoff, both during the active life of the
facility and during the postclosure period.
(h) A description of any proposed engineering
modifications intended to modify groundwater level.
(i) A determination of the horizontal and
vertical flow system, and diagrams that illustrate horizontal and vertical flow
directions of groundwater.
(j) A
proposed hydrogeologic monitoring plan that is in compliance with R
299.4905.
(k) A compilation and
interpretation of data, map s, and charts based on site conditions to support
the conclusions and recommendations of the report.
Notes
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